The present invention relates to a pressure vessel for storing a pressure medium, in particular a gas, having an elongated, pressure-tightly closable hollow body as well as having at least one valve-closable opening for the flowing-out of the pressure medium, the circumference of the hollow body being surrounded by a fiber composite winding and the hollow body being essentially rotationally symmetrical.
A pressure vessel is disclosed, for example, in DE 25 16 395 C2. The present invention is based on the object of optimizing a pressure vessel of the known type, in particular with regard to its connections.
This object has been achieved according to the present invention by the hollow body being provided with a plurality of radially outward-protruding connections distributed symmetrically over its circumference. Two mutually diametrically opposite connections are provided with outflow valves, the others serve for fitting further functional elements. The connections protrude outwardly so as not to be covered by the fiber composite winding. The connections consequently protrude outwards through the fiber composite winding.
In one embodiment of the present invention, the hollow body has a central functional member which is provided with the connections. The member is arranged at the same distance from both end faces of the hollow body and two half-shell-like vessel parts are gas-tightly connected thereto on both sides. Since the connections are located merely in the center of the hollow body, the wrapping of the hollow body with reinforcing fibers is facilitated. This produces a symmetrical distribution of the fiber composite over the circumference of the hollow body.
According to a further feature of the present invention, the hollow body can also be provided only with a functional member arranged at the end. The member is provided with the connections and closed on one side, with a half-shell-like vessel part connected pressure-tightly on its opposite side. The pressure vessel of such a configuration is suitable in particular for arrangement within a gas-cushion protective device for the driver of a passenger car, in which case the device is accommodated in the steering wheel of the car. Here too, the advantages of small installation space and low weight are obtained. In a further embodiment, the functional member is provided with a thicker wall thickness than the vessel parts. The functional member is therefore more stable than the vessel parts, so that the fiber composite winding can be kept thinner in the region of the connections.
Yet another feature of the present invention utilizes winding of reinforcing fibers as a fiber composite winding in a plurality of plies around the hollow body. The fibers are set in predetermined matrix and laminate structure with respect to one another and on the hollow body by a composite resin. In one embodiment, aramid fibers can be provided as reinforcing fibers. These aramid fibers are extremely tough and tear-resistant so that splintering in the event of an unintentional bursting of the pressure vessel is prevented. In comparison with a purely metallic high-pressure accumulator, such a fiber wrapping also offers considerably greater safety reserves before bursting takes place. The pressure vessel can store without any problems gas under a pressure of 400 to 500 bar even over a long period of time, for example the entire service life of a passenger car.
In yet another embodiment of the present invention, at least one layer of reinforcing fibers of the laminate structure is wound in the circumferential direction around the hollow body. In a still further embodiment, the laminate structure has at least two layers of reinforcing fibers which are wound around the hollow body crossing one another and aligned at a acute angle to the axial direction. As a result, allowance is made for the stresses occurring both in the circumferential direction and in the axial direction. Since at least three fibre layers are provided, running at different angles over the outer contour of the hollow body, laminate gaps occurring during production can also be largely closed.